This competing continuation application follows up on our studies of the residual effects of heavy drinking on next-day occupational performance. These effects may represent an important, but relatively unexplored, source of injury and error in the workplace. Several studies, including our own, have indicated that even when blood alcohol concentration (BAGs) is at or near zero, occupational impairment can occur the morning after heavy drinking. These effects have been shown for driving, simulated aircraft piloting, and performance of industrial tasks. Our study proposes to increase understanding of residual effects of heavy drinking by addressing several questions. We will provide further documentation regarding these effects. We will test several hypotheses regarding the mechanism by which heavy drinking affects next-day performance. Using a placebo-controlled randomized trial, we will dose participants with placebo or with a high or low congener alcoholic beverage (to a level of 0.10 g% BAC) the night before they perform exercises on an occupational training simulator. We will monitor participants' sleep to assess sleep disturbance; collect information on hangover symptoms the morning after dosing; and collect data on participants' family history of drinking problems. We will test the following hypotheses: (1) relative to placebo, heavy drinking will degrade next-day occupational performance, and this relationship will be mediated in full or in part by quality of sleep; (2) a high congener alcoholic beverage will affect performance to a greater degree than a low congener beverage and this relationship will be mediated by severity of hangover symptoms; and (3) the residual effects of heavy drinking on next-day occupational performance will be attenuated among participants positive for a family history of alcohol problems, relative to family-history-negative participants. Our occupational model will be merchant ship navigation by maritime academy cadets. Performance will be measured using computer-based interactive ship training simulators.